The effect of replication on the probability of isolating nematophagous fungi from soil

The exact number of replicates required for a given probability of isolating all the species of nematophagous fungi present in a single sample of soil was measured. Using the soil sprinkling technique twenty replicate sub-samples of a sample of farm soil were examined for species. Eight replicates were required under these circumstances to be 95% sure of isolating all the species present. An equation to calculate the number of replicates to achieve a given probability of 100% species isolation is also given.     

Quantification of predatory and endoparasitic nematophagous fungi in soil

Methods were developed to quantify predatory and endoparasitic fungi in soil. The methods were based on previously developed detection techniques and combined with a most probable number estimation. The methods were applied to an agricultural soil fertilized with farmyard manure. Large amounts of farmyard manure resulted in increased amounts of organic matter, numbers of propagules of predatory and endoparasitic fungi, and numbers of bacteria and nematodes.     

In vitro soil receptivity assays to egg-parasitic nematophagous fungi

Soil application of nematophagous fungi for the biological control of plant-parasitic nematodes often fails, and in many cases it has been difficult to reisolate the agent delivered to the soil. A reason for these results could be the inability of the fungi to proliferate in soil. We used a soil–membrane technique to study the capacity of several isolates of the nematophagous fungi Pochonia chlamydosporia and Paecilomyces lilacinus to grow and establish in sterilized and nonsterilized sandy soils from SE Spain and Western Australia. Growth of all fungi tested was inhibited in nonsterilized soil, although there was intraspecific variability in sensitivity among isolates of the same species. With respect to hyphal density, P. chlamydosporia isolate 5 (from Italy) was the least inhibited in nonsterilized soil from both sites. Relative growth analyses confirmed this result for soil from SE Spain, while with this method, P. chlamydosporia isolate 4624 (from Australia) appeared to be least inhibited in the Australian soil. The results indicate that a soil can be more receptive to its indigenous isolates than to nonindigenous isolates. Apparently, soil microbiota can determine the ability of nematophagous fungi to proliferate in soil.     

The living strategy of nematophagous fungi

The infection structures, trophism, and ecological character of nematophagous fungi are reviewed in this article on the basis of data extracted from the literature and the most recent experiments conducted in this area. Traditionally, nematophagous fungi are classified into four groups according to their modes of attacking nematodes: nematode-trapping fungi using adhesive or mechanical hyphal traps, endoparasitic fungi using their spores, eggparasitic fungi invading nematode eggs or females with their hyphal tips, and toxin-producing fungi immobilizing nematodes before invasion. In the present review, we focus on the first two groups. The living strategies of these nematophagous fungi depend on the diversity of their infection structures, such as different traps and spore types, which determine the modes of infecting nematodes. The diversity of trophic modes of nematophagous fungi is an important prerequisite for fungal survival and activity in soil. The abundance and activity of Hirsutella rhossiliensis and H. minnesotensis, representatives of endoparasites and potential biocontrol agents against nematodes, are highly dependent on environmental factors. Comprehensive understanding of the survival and activity of nematophagous fungi in soil is fundamental for the exploitation of these fungi as successful biocontrol agents.     

Psychro-tolerant nematophagous fungi from the maritime Antarctic

Summary The present investigation examines the comparative growth rates, at various temperatures between 4 and 30°C, of two nematophagous fungiMonacrosporium ellipsosporum (Preuss), (Grove), Cooke and Dickinson andM. cionapagum (Drechsler), (Subramanian), Cooke and Dickinson, both isolated from the Antarctic and from Britain. No psychrophilic species were found although the results clearly show that both the Antarctic isolates were psychro-tolerant, displaying lower minimum, optimum and maximum temperatures for growth than the British isolates. A modified form ofM. ellipsosporum isolated from the Antarctic grew only between 4 and 15°C, indicating it to be much better adapted to such cold habitats than the other isolates examined.     

Ecology of nematophagous fungi: Methods of collection,isolation and maintenance of predatory and endoparasitic fungi

The methods employed in a recent investigation into the ecology of nematophagous fungi are examined in detail. The best sources from which fungi can be isolated are examined, and the main field collection and recovery techniques are compared and discussed. Other practical problems considered are the examination of plates, microscopy, identification, isolation and culture methods, maintenance of fungi, the production of nematodes as bait. A summary of the experimental techniques used is given.     

利用黄粉虫分离土壤昆虫病原真菌

利用黄粉虫Tenebrio molitorL.作为寄主从土壤中诱感并分离昆虫病原真菌。结果显示,从吉林市的18个土样中分离出球孢白僵菌(Beauveria bassiana)、金龟子绿僵菌(Metarhiziumanisopliae)和玫烟色拟青霉(Paecilomyces fumosoroseus)。土样中的昆虫病原真菌检出率为77.78%。这表明利用黄粉虫分离土壤中的昆虫病原真菌是一种简单、有效的方法。     

The isolation of keratinophilic fungi from soil and wild animals in South Dakota

Hairs and skin scrapings from 224 wild animals representing 30 species were examined for the presence of keratinophilic fungi. Commercial agars and sterile soil plates moistened with water containing cycloheximide were utilized for culturing specimens. Keratinophilic fungi of the generaTrichophyton andChrysosporium were isolated from 26.8% of the specimens. Using the hair baiting technique of Vanbreuseghem, 54 soil samples were screened for keratinophilic fungi. Eighteen (33.3%) of the samples were positive for the genusTrichophyton. Microsporon spp. were not recovered from the animal hairs or soil samples.

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Zusammenfassung Haare und Haut von 224 wilden Tieren, von dreißig Arten, sind für das Vorkommen von keratinophilen Pilzen untersucht worden. Agar und sterile mit Wasser angefeuchtete Erdbodenplatten mit Cycloheximid sind für Kulturzwecke benützt worden. Keratinophile Pilze von den GattungenTrichophyton undChrysosporium sind von 26.8% der Proben isoliert worden. Mittels der Haarködermethode von Vanbreuseghem sind 54 Erdbodenproben für keratinophile Pilze untersucht worden. Achtzehn der Proben (33.3%) waren für die GattungTrichophyton positiv.Mikrosporon spp. wurden von Tierhaaren oder Erdbodenproben nicht erhalten.

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Approved by the director of the South Dakota Agricultural Experiment Station as Journal Series No. 916.

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Formerly was of the staff of the Bacteriology Department at South Dakota State University.     

The distribution of nematophagous fungi in the maritime Antarctic

Endoparasitic and predatory nematophagous fungi are widely distributed throughout the maritime Antarctic, being recorded along the Antarctic Peninsula as far south as 68° S. Fungi were recorded from 71% of the sites examined with Cephalosporium balanoides and Dactylaria gracilis being the commonest recorded endoparasite and predator, respectively.Endoparasites with adhesive and nematode-attracting conidia were shown to be more abundant and to have a competitive advantage in the Antarctic ecosystem over those parasites requiring their conidia to be ingested before infection could occur. Predators able to form traps spontaneously on germination were shown to be far more abundant than those species with a more saprophytic mode of existence, with constricting rings being the most commonly isolated trapping mechanism. Species capturing nematodes by three-dimensional networks were restricted to bird-associated sites indicating that they are able to grow saprophytically in such organically enriched material.Nematophagous basidiomycetes and phycomycetes were absent except for a single Myzocytium sp. isolated from heated soil.     

The isolation of keratinophilic fungi from African soils

Summary Twenty-seven soil samples from Kenya and 9 from Egypt were investigated for the presence of keratinophilic and pathogenic fungi. No systemic pathogenic fungi was obtained, while a total of 25 dermatophytes belonging to four species was isolated. The majority of the Kenya isolates belonged toM. gypseum, while Egyptian isolates belonged toT. mentagrophytes. Shady sites frequented by humans or animals produced higher incidences of dermatophytes in Kenya than those of the unshady isolated areas.     

Ecology of nematophagous fungi: distribution and habitat

A survey of 161 samples of soil and plant material collected from sites throughout Ireland has shown that nematophagous fungi exist in a wide range of habitats. 205 isolations were made consisting of 11 endoparasitic and 20 predatory species. The commonest endoparasites and their frequency of occurrence were Myzocytium spp. (9·3%), Acrostalagmus obovatus (6·8%) and Harposporium anguillulae (6·2%). Predators were equally abundant, the commonest being Dactylella bembicodes (8·7%), D. mammillata (6·8%) and D. ellipsospora (6·2%). Arthrobotrys oligospora and A. musiformis both had a highly restricted distribution. Adhesive knobs and constricting rings were significantly more abundant than the other trapping mechanisms. All the samples were classified into one of 10 broad habitat types. Of these temporary agricultural pasture, coastal vegetation and coniferous leaf litter had the greatest percentage of sites from which nematophagous fungi were isolated. A number of species showed distinct habitat associations, in particular Arthrobotrys robusta, A. musiformis and Dactylella cionopaga.